luminosity

noun

lu·​mi·​nos·​i·​ty ˌlü-mə-ˈnä-sə-tē 

plural luminosities

1

a

: the quality or state of being luminous

b

: something luminous

2

a

: the relative quantity of light

b

: relative brightness of something

3

: the relative quantity of radiation emitted by a celestial source (such as a star)

Synonyms

• brightness
• brilliancy
• brilliance
• lightness

Examples of luminosity in a Sentence

the luminosity of the fireflies made for an enchanting nighttime show

Recent Examples on the Web

The new star shines because its surface is hot, but the energy fueling that luminosity percolates up from its core. —Luke Keller, Space.com, 7 Sep. 2025

Above the fog line, more hours of sun and brilliant luminosity bring distinctive structure to the Pinot Noir and a voluminous, fleshy texture to the Chardonnay. —Mike Desimone, Robb Report, 7 Sep. 2025

Scientists ultimately settled on a feeding black hole at the heart of a far-distant galaxy as the most likely engine for 3C 273’s ridiculous luminosity. —Phil Plait, Scientific American, 4 Sep. 2025

The new star shines because its surface is hot, but the energy fueling that luminosity percolates up from its core. —ArsTechnica, 27 Aug. 2025

Word History

Etymology

borrowed from Middle French & Medieval Latin; Middle French luminosité, borrowed from Medieval Latin lūminōsitāt-, lūminōsitās, from Latin lūminōsus "full of light, luminous" + -itāt-, -itās -ity

First Known Use

1634, in the meaning defined at sense 1a

Rhymes for luminosity

• adiposity

Kids Definition

luminosity

noun

lu·​mi·​nos·​i·​ty ˌlü-mə-ˈnäs-ət-ē 

plural luminosities

1

: the quality or state of being luminous : brightness

2

: something luminous

Medical Definition

luminosity

noun

lu·​mi·​nos·​i·​ty ˌlü-mə-ˈnäs-ət-ē 

plural luminosities

1

: the quality or state of being luminous

2

a

: the relative quantity of light

b

: the comparative degree to which light of a given wavelength induces the sensation of brightness when perceived